Weeds of Container Nurseries in the United States

	Spurges are summer annual weeds that flourish in warm weather, but in warmer climates some can persist into late fall. Plants flower in summer and early fall then die after frost. Flowers are greenish-white. Spurges are some of the most common warm-season weeds in container nurseries. Various species are important in different nurseries because of different weed introductions, production practices, and weed management strategies. Each exudes a milky sap when stems or leaves are broken.
garden spurge	Control Guidelines for Spurges: Because spurges flower when young and have little or no seed dormancy, weed populations can increase rapidly. Remove plants when young to reduce seed production. They are time consuming to hand weed due to the number of seedlings that form. Some species may forcefully discharge seeds. Spurges are well controlled by most preemergence nursery herbicides containing a dinitroaniline, but less well controlled by oxadiazon or oxyfluorfen.
	Garden Spurge (Chamaesyce hirta or Euphorbia hirta). This species is a prostrate to ascending spurge with distinctively uneven leaves and a large seedhead. It is a prolific seeder. Seed have no dormancy and germinate quickly. Garden spurge is more easily controlled with preemergence herbicides than other spurges, but it tends to spread more rapidly. Garden spurge is most common in southern nurseries, but it is spreading.
spotted spurge	Spotted and prostrate spurges (Chamaesyce maculata, C. humistrata, C. cordifolia and others). These similar spurges have prostrate to ascending stems with round or oblong leaves; some have a large dark spot on the leaf blade. However, presence or absence of the dark spot is not diagnostic to the identification of these species. Seedlings are very small but will flower when young. A prolific seeder; seeds have no dormancy and germinate quickly. These are the most common summer annual broadleaf weeds in many container nurseries.
hysop spurge	Hyssop spurge (Chamaesyce hyssopifolia). Foliage of this species is similar to spotted spurge but plants are larger, with a more upright growth habit, and leaves are longer than wide with an uneven base. Plants have long, smooth, branched stems, often red in color, and a stout tap root. It is a prolific seeder; seeds have little or no dormancy and germinate quickly. It is somewhat more tolerant to herbicides than prostrate spurge but well controlled by many preemergence herbicides labeled for use in container nurseries.
nodding spurge	Nodding spurge (Chamaesyce nutans). This species is very similar to hyssop spurge. Younger foliage is softly hairy, losing hairs with age. Occurrences of nodding spurge in nursery crops appear to be increasing. Preliminary research suggests that nodding spurge is somewhat less susceptible to preemergence herbicides commonly used for spurge control.